Question: Simplify the following expression: $k = \dfrac{10ab + 20cb}{15b^2 + 30cb} + \dfrac{25cb + 5ab}{15b^2 + 30cb}$ You can assume $a,b,c \neq 0$.
Answer: Since the expressions have the same denominator we simply combine the numerators: $k = \dfrac{10ab + 20cb + 25cb + 5ab}{15b^2 + 30cb}$ $k = \dfrac{15ab + 45cb}{15b^2 + 30cb}$ The numerator and denominator have a common factor of $15b$, so we can simplify $k = \dfrac{a + 3c}{b + 2c}$